Hitherto, in a motor or a transformer, there is a core having a structure in which thin plate-like silicon steel plates punched by a press are laminated and integrated by caulking or welding. Besides, as a stator of a motor, there is a split core structure in which a core is divided in order to increase the occupation ratio of a winding and to improve the workability of the winding, and this contributes to the miniaturization of the motor and the improvement in performance.
For example, in patent document 1 (JP-A-61-124241), there is a split core having a structure in which a stator of a motor is completely divided into each teeth, and after a winding is provided at the split core, a concave part and a convex part provided in a divided part are coupled to each other, and the stator is formed. Here, there is adopted a division shape according to an object, for example, a split core shape in which a ring-shaped core back is divided and which includes a part of the core back and a teeth part, or a split core shape in which a ring-shaped core back is not divided, and a division is made between the teeth and the core back. In addition to these, as conventional split core structures, for example, there are ones disclosed in following patent document 2 to patent document 6.
Patent document 1: JP-A-61-124241
Patent document 2: JP-A-63-299752
Patent document 3: JP-A-2001-128394
Patent document 4: JP-A-7-59278
Patent document 5: JP-A-2004-173440
Patent document 6: JP-A-2005-102424